1. Field of the Invention
The present invention relates to an absorbent pair refrigeration system wherein the refrigerant is desorbed from a complex compound comprised of the refrigerant and a chemical absorbent using electromagnetic wave energy, and in particular microwave energy.
2. Description of the Relevant Art
Existing absorbent pair refrigeration systems utilize a gaseous refrigerant which is alternately adsorbed onto and desorbed from a chemical absorbent. The refrigerant and absorbent are referred to as absorbent pairs, and a complex compound is formed by adsorption of the refrigerant onto the absorbent. In typical systems, a refrigerant comprised of a low pressure polar gas, which has been vaporized in an evaporator, is adsorbed onto an absorbent comprised of an inert solid metal salt. Once the refrigerant has been fully adsorbed, the complex compound comprised of the refrigerant and the salt is heated to drive off the refrigerant. The resulting high-pressure refrigerant gas is then directed to a condenser, where it is converted back into a liquid phase. The high-pressure liquid refrigerant is then directed to the evaporator, wherein the refrigerant is evaporated and heat is adsorbed by the refrigerant from the atmosphere to provide the desired cooling effect.
In these prior art systems, an electrical or gas powered heater is used to heat the complex compound in order to drive off the refrigerant. The heat is transferred to the complex compound primarily through conduction, and the canister which contains the absorbent and in which the adsorption and desorption reactions occur is typically constructed of metal to aid in the transfer of heat. The combination of the canister, the absorbent and the heater is commonly called a sorber. The canister is usually provided with internal metal fins or other similar conductive means to segment the absorbent to thereby shorten the thermal diffusion path length between the wall of the canister and the absorbent to further aid in the transfer of heat to the complex compound.
During the desorption reaction, the sorber adsorbs a substantial amount of sensible heat, which must then be rejected prior to the adsorption reaction so that the absorbent is sufficiently cooled to enable it to reabsorb the refrigerant. This sensible heat reduces the COP of the refrigeration system and increases the cycle time between the desorption and adsorption reactions, thereby reducing the cooling capacity of the absorbent pairs. Furthermore, prior art systems often employ extraneous cooling means to cool the sorber during the cycle between the desorption and adsorption reactions, which is referred to as the letdown or cooling cycle. These means include using cooling fins attached to the exterior of the canister and running refrigerant through tubing through the core of the sorber. Both of these means add complexity and cost to the sorber design.